1.0 What is asthma?

Asthma is a condition in which the airways of the lungs become inflamed, which results in the airways becoming either constricted or completely blocked, impeding normal breathing.

However, in asthma, unlike other diseases such as emphysema and chronic pulmonary obstructive disease, this obstruction of the lungs is reversible, either spontaneously or with medication.

The process is as follows: air reaches the lung by passing through the windpipe (trachea), which divides into two large tubes(bronchi), one for each lung.

Each bronchi further divides into many little tubes (bronchioles), which eventually lead to tiny air sacs (alveoli), in which oxygen from the air is transferred to the bloodstream, and carbon dioxide from the bloodstream is transferred to the air. Asthma involves only the airways (bronchi and bronchioles), and not the air sacs.

The airways are cleaned by trapping stray particles in a thin layer of mucus which covers the surface of the airways. This mucus is produced by glands inside the lung, and is constantly being renewed. The mucus is then either coughed up or swept up to the windpipe (trachea) by cilia, tiny hairs on the lining of the airways. Once the mucus reaches the throat, it can again be coughed up or, alternatively, swallowed.

Although everyone's airways have the potential for constricting in response to allergens or irritants, the asthma sufferers airways are oversensitive, or hyperreactive. In response to stimuli, the airways may become obstructed by one of the following:

constriction of the muscles surrounding the airway;

inflammation and swelling of the airway; or

increased mucus production which clogs the airway.

Once the airways have become obstructed, it takes more effort to force air through them, so that breathing becomes laboured. This forcing of air through constricted airways can make a whistling or rattling sound, called wheezing. Irritation of the airways by excessive mucus may also provoke coughing.

Because exhaling through the obstructed airways is difficult, too much stale air remains the lungs after each breath. This decreases the amount of fresh air which can be taken in with each new breath, and this lack of fresh air means that less oxygen is available for the whole body. This decreased supply of oxygen is what makes an uncontrolled asthma attack so serious.

1.1 What is an asthma attack?

An asthma attack can be defined as any shortness of breath which interrupts the sufferers well-being and requires either medication or some other form of intervention for the individual to breathe normally again.

1.2 What is wheezing?

Wheezing is the whistling or rattling sound that occurs when air flows through obstructed airways. At the start of an asthma attack, wheezing usually only occurs while exhaling, or breathing out, but as the attack progresses, wheezing may then be heard both while inhaling and exhaling. If after the attack progresses further, the patient then stops wheezing, this may indicate that many bronchioles (small airways) have become completely blocked, which is a very serious condition.

1.3 Do all people with asthma wheeze?

Although wheezing is extremely common in people with asthma, not all these people wheeze, and sometimes wheezing is so slight, it can only be heard with a stethoscope. With some sufferers, coughing is the only symptom present. Similarly, children with chronic coughs may have asthma, even though no wheezing is present. Diagnosis of such children with asthma can be made if their peak flow improves when given an inhaled bronchodilator.

1.4 Is asthma hereditary?

No, asthma itself is not hereditary, but there does seem to be a hereditary component to the tendency to develop asthma. If neither parent has asthma, the chances of each of their children having asthma are less than if one or both parents has asthma. Children don't inherit asthma itself, but the tendency to develop it. Whether or not an individual develops asthma is also now thought to be influenced by their exposure, particularly in childhood, to various other factors such as infections, irritants, and allergens.

2.0 How is asthma diagnosed?

Asthma is diagnosed based on a physical examination, personal history, and lung function tests. The physical examination looks for typical asthma symptoms such as wheezing or coughing, and the personal history provides additional clues such as allergies or a familial tendency towards asthma. Lung function tests may be as simple as measuring peak flow with a peak flow meter, or

using a simple spirometer, or may involve a battery of spirometry tests with sophisticated computer analysis.

2.1 What is a spirometer?

A spirometer is a machine for testing lung function that you breathe in and out of through a tube attached to a mouthpiece. You are usually given nose clips so that all the air you breathe goes through the machine. It can measure a fair number of characteristics of your lungs, including:

FVC, or forced vital capacity, which is the amount of air that you can exhale forcefully after taking a deep breath FEV 1, or forced expiratory volume in one second, is the amount of air that you can breath out during the first second of a forced exhalation.

Peak flow, or PEF, is described in section 2.2, What is a peak flow meter?.

2.2 What is a peak flow meter?

A peak flow meter is a little plastic device which you blow hard into, after having taken a deep breath. It records the rate at which you've blown into it in litres exhaled per minute (litres/min). This is called the peak expiratory flow rate (PEFR). The meter is essentially a cylinder with a mouthpiece at one end, a place for the air to escape at the other end, and a calibrated meter along the side. When you blow into it, a marker is pushed along the scale and comes to rest at a point which indicates your PEFR. Since you want to measure your maximum peak flow, it is important to take a deep breath and blow as hard and as fast as you can. Many people with asthma find that their maximum peak flow provides a good objective measure of how their asthma is doing, so peak flow meters now are used extensively for self-monitoring of asthma, and also for monitoring the effectiveness of asthma medications.

3.0 How is asthma normally treated?

Treatment of very mild asthma usually tries to relieve occasional symptoms as they occur by use of short-acting, inhaled bronchodilators. In all but the mildest cases of asthma, however, treatment attempts to alleviate both the constriction of the airways and the underlying inflammatory disease process, through the use of both bronchodilators and anti-inflammatories.

Bronchodilators are drugs which open up or dilate the constricted airways, while drugs aimed at reducing underlying inflammation of the airways are called anti-inflammatories.

For asthma which is strongly triggered by allergies, such as pollen, household pets, and moulds, allergen avoidance can often greatly reduce the amount of medication needed to control the asthma. See the section on allergies on this site for more information.

Taking anti-inflammatory drugs (usually inhaled corticosteroids) daily for moderate to severe asthma is a relatively recent approach to treating asthma, based on recent advances in the understanding of the asthma disease process. The idea behind it is that if the underlying inflammation of the airways is reduced, the bronchi may become less hyperreactive, making future attacks less likely. Such anti-inflammatory therapy, however, must be taken regularly - usually on a daily basis - in order to be effective.

Countries with a high usage of anti-inflammatory treatment for asthma have seen reductions in deaths due to asthma attacks, and reduced levels of hospitalisation for asthma sufferers. Information such as this is leading doctors to recommend the use of anti-inflammatory treatments for asthma as soon as it is clear that symptoms justify such an approach.

3.1 How is an acute asthma attack treated?

An acute asthma attack is treated by use of bronchodilators to reduce the constriction of the airways. Intravenous adrenalin and theophylline are often given immediately in emergency rooms for this purpose, if short-acting bronchodilators given by nebuliser have not sufficiently controlled the attack.

Once the acute attack is over, anti-inflammatories may be used to reduce the inflammation of the airways. Inhaled steroids are usually the first choice, but for a sufficiently severe attack, oral steroids such as prednisone may also be given.

4.0 What are the common triggers of asthma?

The most common triggers of asthma are:

viral respiratory infections, such as influenza (the flu) or bronchitis;

bacterial infections, including sinus infections hay fever, or other forms of allergic rhinitis (allergens which particularly irritate the nasal passages)

irritants, such as pollution, cigarette smoke, perfumes, dust, or chemicals

sudden changes in either temperature or humidity, especially exposure to cold air

allergens, for people with allergies, such as          

        pollen,

       stress

       exercise.

4.1 Can gastric reflux trigger asthma?

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Yes, gastric reflux can act as an irritant which triggers asthma. Reflux, properly known as gastroesophageal reflux, occurs when the liquids in the stomach pass up the oesophagus, or feeding tube. Because these liquids are usually highly acidic, they can irritate and inflame the oesophagus, and also the airways of the lung, should any of this liquid be aspirated. This irritation can trigger an asthma attack.

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Asthma attacks caused by reflux are more common at night, for it is easier for material to pass up the oesophagus when one is lying down. Some simple treatments to prevent reflux include raising the head of the bed, not eating close to bedtime, or in more serious cases using medications which reduce the amount of acid produced by the stomach. Consult your doctor.

Different Medications

5.0 What are the major classes of asthma medications?

There are six major classes of asthma medications:

1.steroidal anti-inflammatories,

2.non-steroidal anti-inflammatories,

3.beta-agonists,

4.xanthines.

5.anticholinergics, and

6.anti-allergics.

The first two categories of drug treat the underlying inflammation of the lung. All steroidal anti-inflammatories are glucocorticosteroids, which are entirely different from the anabolic steroids that are illegally used by athletes and bodybuilders to improve their performance. There are many different glucocorticosteroids available for the treatment of asthma, almost all available via an inhaler to minimise the amount of side effects (see section 6.3). These are the types prescribed by doctors for the vast majority of people with asthma. The non-steroidal anti-inflammatory currently available is cromolyn sodium. Cromolyn sodium blocks both the release of histamine and inflammatory mediators, which means that although it blocks the inflammatory response, it cannot reverse inflammation once it has taken place. For this reason, it is more properly classed as an anti-allergic, since it is mostly commonly taken for asthma that has a strong allergy component.

The second two classes of asthma medications, beta-agonists and xanthines, are both bronchodilators. Beta-agonists are chemically related to adrenaline. They are usually taken in inhaled form, and the majority are short-acting. The major xanthine, theophylline, is taken orally. Theophylline is chemically related to caffeine in coffee and teine in tea which are also xanthine

derivatives.

Anticholinergics, the fourth class of medication, work by blocking the contraction of the underlying smooth muscle of the bronchi.

The last class, the anti-allergics, has been included because the two anti-allergic drugs, cromolyn sodium and ketotifen, are commonly taken for the prevention of asthma that has a strong allergy component. Cromolyn sodium blocks the release of histamine from mast cells, which acts to prevent asthma flares since histamine is a very strong bronchoconstrictor. However, it isn't considered an antihistamine because it cannot prevent the effects of histamine once the histamine has been released from the cell. Similarly, it blocks the release of inflammatory mediators from the mast cell, and so prevents the inflammatory response, although it cannot reverse inflammation once the mediators have been released.

5.1 Are some asthma drugs banned in athletic competitions?

The determination of whether a drug or substance is banned or allowed in amateur athletic competitions is not based on whether it is medically necessary. Rather, such a determination is based on whether the substance in question can be performance-enhancing and offer an unfair competitive advantage. There are several organizations that make this decision and an athlete on an anti-asthma drug should check with his coaches, physician, and appropriate athletic authority. Different athletic organisations may differ on what is banned or allowed.

An athlete cannot assume that an over-the-counter (OTC) status of any drug - in other words, one available from a pharmacy without prescription - implies that it is allowed in athletic competitions; as many OTC agents (e.g. combination decongestant-bronchodilators containing ephedrine) or herbal preparations bought in food stores contain stimulants useful for asthma but banned in certain athletic competition settings.

5.2 What medications should people with asthma be careful about taking?

Aspirin can trigger an asthma attack in approximately one in five sufferers. This is especially common in those people who also have nasal polyps. Other types of drugs similar to aspirin, known as non-steroidal anti-inflammatory drugs (NSAIDs), of which ibuprofen is the best-known example, are also dangerous. Paracetamol may be used as an alternative for anyone who suspects   that they might have aspirin sensitivity.

Cough medicines should also be treated with caution. In general, taking a medicine to suppress a productive cough (one which is bringing up mucus) is not a good idea, since the mucus can obstruct the airways and also irritate them further.

Antihistamines, however, should not pose a problem for most people with asthma, in spite of many warning labels.

Individuals taking theophylline should be careful when taking any of the following medications: the ulcer medications cimetidine and troleandomycin, beta-blocker drugs such as propranolol, and the antibiotics erythromycin and ciprofloxacin. These medications may increase the concentration of theophylline in the bloodstream, possibly even to the toxic level (see section). People taking theophylline should be alert for signs of possible toxicity such as rapid or irregular heartrate, nervousness, or nausea, when taking these medications. In fact, people taking theophylline should check with their physician before taking any OTC medication, as the list of drugs, including antihistamines, which affect theophylline levels is almost endless.

Beta-blockers, usually taken for hypertension, can pose problems even for those individuals not taking theophylline. Beta-blockers work by blocking the hormone adrenalin, but as adrenalin and other adrenergic drugs help keep airways dilated, the use of beta-blockers may aggravate asthma symptoms. Newer drugs without such side-effects are now available to substitute for beta-blockers in almost all cases.

5.3 Why do I need a blood test when taking theophylline?

Theophylline is commonly used as a second-line agent in the management of asthma, after beta-agonists and anti-inflammatories. Unfortunately, its therapeutic level is quite close to its toxicity level. This means that the dose that the individual needs to get the full benefit of the drug is not very much lower than the dose which causes side effects, which range from unpleasant to dangerous. This would not be such a problem if there were not such large variations in the rate at which people metabolise theophylline. If a group of people are given the same dose of theophylline, the concentration of the drug in their bloodstreams may vary by up to a factor of seven, dependent on their metabolism, drinking habits, whether they are a smoker, and a number of other factors. Therefore, the best way to monitor that a person is receiving the optimal amount of theophylline is to take a blood level concentration.

5.4 What is "thrush mouth" and how can I avoid it?

Thrush, or thrush mouth, is the popular term for a yeast infection (candida albicans) in the back of throat. The major symptom of thrush is a white film located at the back of the throat and tonsil area. It is usually cured by the use of an antifungal mouthwash.

Thrush can be a side effect of taking inhaled corticosteroids, since steroids alter the local bacteria and fungal population of the mouth, enhancing fungal growth. The way to avoid this complication is to ensure that the back of the throat doesn't remain coated with corticosteroid after use of the inhaler, either by using a spacer or by rinsing the mouth thoroughly afterwards. Unfortunately, some people still get it even when they are very thorough about rinsing. In difficult cases, switching from a pMDI to a dry powder inhaler (see section 2.3) may help with this condition.

Inhalers, spacers, nebulisers etc.

6.0 What kinds of inhalers are there?

There are two main types of inhalers: the pMDIs (pressurised metered dose inhalers) and dry powder inhalers.

A pMDI consists of an aerosol unit containing the treatment and a plastic mouthpiece. This is currently the most common type of inhaler, and is widely available, but contains propellants - generally ozone-damaging CFCs - which some people find irritating to their throat and lungs. If you are concerned about their environmental impact, pMDIs are now available which are CFC-free. The pMDI also requires you to coordinate a hand movement which dispenses the treatment with sharp inhalation to get it into your lungs, which some people find difficult to achieve. There is a type of pMDI now available which is actuated by inhalation alone, if this is a problem. However, many doctors are moving to dry powder inhalers which overcome many of the problems of pMDIs.

Dry powder inhalers: these work by dispensing a tiny amount of dry powder, which is then inhaled without the assistance of propellants. There is evidence to suggest that dry powder inhalers produce a higher level of pulmonary deposition than the pMDIs - in other words, more of the treatment gets to the area that needs it. Some dry powder inhalers contain just pure drug, but others also contain a small amount of lactose. In Europe, doctors are increasingly switching patients who have difficulty with pMDIs, or whose treatment does not seem to be effective when delivered by pMDIs, to dry powder inhalers.

6.1 What is a spacer? What is a holding chamber?

Pressurised metered dose inhalers (pMDIs) for asthma medications typically consist of a metal aerosol canister (containing the medication and a propellant) in a plastic sleeve with a mouthpiece. The patient inhales a metered dose of a medication through the mouthpiece. Most people find it difficult (at least initially) to time the spraying of an pMDI and the inhalation of the medicine: the patient must exhale fully and inhale and release the metered dose just at the beginning of the inhalation.

All too often the puffs are mis-timed, and only make it part of the way into the airways, and some of the medication is invariably deposited into the mouth and on the back of the throat instead of into their lungs. In addition to being less effective, this can lead to other side effects (e.g. for inhaled steroids, an increased potential for thrush, an oral fungal infection described in section 5.5). Some people find that dry powder inhalers can help avoid some of the problems associated with inadequate pMDI inhalation, as they do not require such co-ordination.

Several devices have become available that address these difficulties with pMDIs to varying degrees. The devices are generally referred to as "spacers" since they place additional space between the patient and the pMDI. The medication is sprayed into the spacer instead of the mouth. As the patient inhales, the column of medication passes through the mouth and throat relatively  quickly, leaving little opportunity for the medication to be deposited in the mouth or throat. This is a more efficient means of delivering the medication to the airways where it is most needed.

A "holding chamber" is a more sophisticated device. It is a sealed chamber (once the inhaler is inserted) that traps and holds the medication, allowing the patient to spray the medication into the chamber and take a few seconds to inhale the medication. Since the medication is temporarily suspended in the holding chamber, the timing of the inhalation is not nearly as critical as with

simple spacers or no spacer. The patient should exhale as completely as possible before taking in any medication, so that the medication can be inhaled as deeply as possible.

In addition to improving the timing of the inhalation, a holding chamber makes it possible to take in the medication more slowly than is possible without a spacer or with a simple spacer. This is important for the symptomatic patient, since rapid inhalation of the medication is more likely to trigger coughing and cause the patient to lose the medication before it has had a chance to be  absorbed.

The most effective way to use the spacer is to dispense each dose (puff) of the drug into the spacing chamber and then inhale spearately, i.e. the sequence should be puff, inhale, puff, inhale etc. This process should be repeated according to the number of doses (puffs) your doctor has prescribed. If the whole dose is inhaled at once, this can result in a sub-optimum or lower dose, reaching the lungs.

Some spacers are clear so that you can see the puff of medicine, and so that you can see when the medication is building up on the inside, indicating that the spacer needs cleaning.

Spacers and holding chambers need periodic cleaning; clean carefully, following the manufacturer's instructions so as not to damage any delicate internal parts, or allow moulds or other contaminants to be introduced.

There are special holding chambers for younger children.

6.2 Why are so many asthma drugs taken via inhaler?

Medications taken orally almost always have a much higher systemic concentration (concentration in your entire body) than inhaled medications, as they have to get to your lungs and windpipe (the area they need to treat) through the bloodstream. So if the side effects are due to systemic concentrations, then an inhaled drug is less likely to have these side-effects, or may have them much less severely.

The idea behind an inhaler is that the full dose is delivered to the lungs, where it is immediately absorbed by the lung tissue, and starts to take effect locally. Excess drug may be absorbed by the bloodstream and delivered to the rest of your body, but this amount tends to be minimal. So your lungs receive an immediate, high concentration of the drug, and the rest of your body receives very little.

6.3 How can I tell when my pMDI is empty?

You can tell whether a pMDI (pressurised metered dose inhaler) canister is empty by taking the canister out of the mouthpiece and placing it in a container of water. If the canister sinks, and lies horizontally on the bottom, then it is full. If it floats horizontally at the top, it is empty. The intermediate stages, floating vertically at the bottom of the container, floating vertically at the top of the container, and floating at the top at an angle of 30 to 40 degrees, indicate that it is roughly three-quarters full, half full, and a quarter full, respectively.

An alternative method is to count every usage, and tally this figure against the total number of doses contained in the pMDI (this will be listed in the information leaflet enclosed with the pMDI).

Some dry powder inhalers have indicators telling you when the number of doses left is low.

6.4 What is a nebuliser?

A nebuliser is a device that uses pressurised air to turn a liquid medication into a fine mist for inhalation. If you have ever received emergency treatment for asthma, you have probably used a nebuliser.

The term nebuliser is often used to describe both the pump that pressurises the air, and the part that holds and "nebulises" the medication. There are hand-held nebuliser units and ones with masks that you strap onto your face.

The pressurised air typically comes from a portable pump unit, which forces air through a plastic tube into the plastic nebuliser unit. Inside, the nebuliser unit acts much like a perfume atomiser, creating a fine mist that is directed either through a tube that you inhale through or a mask that directs the mist into your nose and mouth.

Since the nebulizer takes a few minutes to deliver the medication, you inhale it over a longer period of time than if you were using an inhaler. This can really help, especially if your bronchial passages are not fully open and you're taking a bronchodilator. As you breathe the medication, your lungs can gradually accept more and more of the medication. In addition to the medication, many people find the accompanying mist (typically a sterile saline solution) to be soothing.

For very young children, the nebuliser is the only practical means of administering inhaled medications. Older children and adults have the options of using pMDIs and a variety of spacers to make the timing a bit easier, or switching to a dry powder inhaler. The doctor overseeing the treatment decides which is the most effective/appropriate delivery mechanism.

6.5 What is Asthma? Who gets it?

Asthma is becoming more common in both adults and children throughout the world, and rates in developing countries are beginning to catch up with those in the industrialised countries. Asthma is thought to affect around five to 10 percent of adults and 10 to 15 per cent of children with varying degrees of severity.

No one really knows why the numbers are rising, but the reasons for the rise are being discussed throughout the world.There are probably some reasons for the increase in asthma, such as the western life-style which involves spending more time spent indoors. For example, more children watch television than they did 30 - 40 years ago.

As yet there is no actual cure, but there are several kinds of treatment which can help to control the symptoms, prevent long-term damage to lungs, and allow the majority of people with asthma to lead normal lives.

The number of deaths from asthma up until recently was increasing, especially among elderly people. However,the number of deaths is slowly descreasing, however, it is still sadly at a level for concern.

People with asthma develop a variety of symptoms as a result of their lower airways (the tubes in the lungs) becoming obstructed due to inflammation. When the lining of the airways becomes inflamed, they become super-sensitive so that they respond to various triggers by narrowing excessively. Just what sets off this process in the first place will depend on the individual, but it may be:

a specific substance to which they are allergic (an allergen). Common allergens include the house dust mite and animal dander, for example

a chemical sensitiser, which may be found at work for example

             infection

             exercise

Asthma is a very common illness. Childhood asthma is the most frequent cause of missed school days. Children who develop asthma usually belong to a group of people whom doctors describe as 'atopic'. By this, they mean that the

person has inherited a gene which makes them liable to allergy. An allergic person will develop some kind of allergic illness if they encounter an allergen which triggers an allergic response. The allergic illness may take the form of asthma,but members of atopic families often also suffer from other allergic conditions such as hay fever and eczema. They mostly start in childhood, but can sometimes develop later.